The purpose of this proposed study is to characterize the experience of subtypes of insomnia (initiation, maintenance, and daytime fatigue or sleepiness) in HIV-infected persons, and to identify biomarkers associated with these subtypes such that a more targeted intervention can be developed and tested to improve sleep, reduce fatigue, and thereby enhance quality of life in HIV-seropositive men and women. In Phase I, descriptive data will be gathered on a cross-sectional sample of 250 or more subjects in year 01-02 to identify relationships between insomnia subtypes and selected biomarkers. In Phase II, longitudinal data will be gathered on up to 100 men and 100 women, asymptomatic at Time 1, to characterize insomnia subtypes as they develop over time. There are four aims: 1) test relationships between objective sleep disturbance (wake/sleep rhythm, total sleep time day and night, wake after sleep onset) and common gene polymorphisms, selected metabolic parameters (insulin, glucose, adiponectin, leptin, free fatty acids), HIV severity indicators (viral load, CD4 cell count), anthropometric measures of lipodystrophy, and quality of life (fatigue, cognitive function, depressive symptoms) for both men and women who are HIV-seropositive; 2) test relationships between subjective sleep disturbances (time to fall asleep, awakenings) and gene polymorphisms, metabolic parameters, HIV indicators, anthropometrics, and quality of life for both men and women; 3) describe onset of symptoms and medication adherence over time in initially asymptomatic subjects who are HIV-seropositive; and 4) test which sets of variables significant in Aim 1 and Aim 2 best predict the onset of insomnia subtypes. It is hypothesized that the set of biomarkers that best predict the onset of initiation insomnia may differ from the variables that predict maintenance insomnia or daytime quality of life measures.